Liquid crystal display device

Abstract

A liquid crystal display device comprises a pair of substrates, a transparent electrode formed on each of the substrates, an orientation film covering the transparent electrode and a liquid crystal sealedly sandwiched between the pair of substrates, wherein the orientation film comprises a polyimide which is formed by a condensation polymerization of 2,2-bis[4-(4-aminophenoxy)phenyl]propane as an amine component and 1,2,4,5-benzenetetracarboxylic dianhydride as an carboxylic acid component, and is subjected to a uniaxial orientation treatment, and the liquid crystal has a smectic layer structure with its bending direction which is aligned with the direction of the uniaxial orientation treatment.

What is claimed is: 
     
       1. A liquid crystal display device comprising a pair of substrates,   a transparent electrode formed on each of the substrates,   an orientation film covering the transparent electrode and   a liquid crystal sealedly sandwiched between the pair of substrates,   wherein the orientation film comprises a polyimide which is formed by a condensation polymerization of 2,2-bis[4-(4-aminophenoxy)phenyl)propane as an amine component and 1,2,4,5-benzenetetracarboxylic dianhydride as an carboxylic acid component, and is subjected to a uniaxial orientation treatment, and   wherein the liquid crystal has a smectic layer structure having a bending direction aligned with the direction of the uniaxial orientation treatment.   
     
     
       2. The liquid crystal display device of claim 1, wherein a direction of the uniaxial orientation of the orientation film covering the transparent electrode formed on each of the pair of substrates is the same. 
     
     
       3. The liquid crystal display device of claim 1, wherein the polyimide film is formed by the condensation polymerization in addition with a small amount of 1-amino-4-trimethoxysilylbenzene as a further amine component. 
     
     
       4. The liquid crystal display device of claim 3, wherein the amount of 1-amino-4-trimethoxysilylbenzene satisfies in a molar ratio defined by the formulas: ##EQU3## wherein A, B and C represent molar ratio of 1,2,4,5-benzenetetracarboxylic dianhydride, 2,2-bis(4-(4-aminophenoxy)phenyl]propane and 1-amino-4-trimethoxysilyl benzene, respectively.